Telephone-exchange system.



H. G. WEBSTER.

TELEPHONE EXCHANGE SYSTEM.

APPLlCATION FILED MAY 29.1914.

Patented May 21,1918.

3 SHEETS-SHEET l.

wrrEssEs H. G. WEBSTER.

TELEPHONE EXCHANGE SYSTEM.

APPLxcATioN FILED 11.111.29.191,

1,266,645, l Patented May 21,1918.

3 SHEETS-SHEET 2.

wrrNEssEs Q llHg INVENTOR H. G. WEBSTER. `TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED MAY 29, 19H.

Patented May 21, 1918l INVENTOR HARRY G, WEBSTER, 0E CHICAGO, rLLiNois,'AssiGNoE BY iviEsNE ASSIGNMENTS, To

JAMES E. GARFIELD, TRUSTEE, 0E' CLEVELAND, oHio.

TELEPHONE-EXCHANGE SYSTEM.

' specification.

relates to telephone exchange systems, and particularly to that type ofsystems known as call distributing systems, in which the lines ofcalling subscribers are automatically extended to any one of a pluralityof operators ypositionsat which the call is answered. The desired Myinvention connection is then completed by means under control of theoperator who has answered the calling line. The object of my inventionconsists in the provision of improved means `for automatically extendinga calling line to an idle operator whereby greater speed and reliabilityof operation than has heretofore been possible is secured.

In prior call distributing systems in which calling lines areautomatically extended to trunk lines terminating in plug ended cords,traveling switches have been employed interposedv between the callinglines and the trunks for effecting the auto-- matic extension of thecalled lines. In accordance with the present invention, I avoid the useof traveling switches operated in response to each call, and insteadsecure the automatic extension of the calling lines by means ofcorrelated relay groups associated with each trunk line. A sufficientnumber of trunk lines are associated with each line group to care forthe maximum calling trafiic present at any one time in the line group,and these trunk lines terminate in plug ended cords before answeringOperators. The relays of each such group'are selectively operated toconnect a calling line with the trunk line to which the relays belong,and a relay associated with each trunk line operates at the linstantvofselection to temporarily disassociate from the line group that trunkline thus engaged. In addition, each line group and associated trunkgroup is provided with a guarding switch and con- ,trolling devices soarranged that in case of abnormal delay or defective operation at thetime of selection, thefswitch will be op- Speccation of Letters Patent.

Patented May 21, 1918.

Application filed May 29, 1914. Serial No. 841,798.

erated to disassociate that portion of the ap- A paratus in defectivecondition.

I have illustrated a preferred embodiment of my invention in theaccompanying drawings, in which Figure 1 and Fig. 2 illustrate a linegroup with its controlling apparatus and relays for selecting a callingline in such group. Fig. 3 illustrates the associvated group of plugended trunk cords and that portion of the apparatus more directlyassociated with the cords.

Referring to Fig. 1, I have shown at A the complete circuits of one lineterminating at the central oflice in the line relay 41 and in thecut-off relay 43. A second similar line is indicated by the line relay42 and cutolf relay 44. The line relays 41 and 42, respectively, controlthe circuits of local relays 121 and 131, and additional lines areindicated by the local relays 122 and 132. Each line is or may beprovided with a plurality of connecting spring jacks connected asindicated at 221 and 231, and with connecting terminals on connectorswitches as indicated at 222 and 232.

Referring to Fig. 3, I have shown at C the complete circuits and.apparatus of one of the group of plug ended trunks associ-l ated withthey line group of Fig. 1, and have indicated a plurality of such trunksby the conductors terminating in. plug D and by the circuit controlledat the left hand contact levers of relays 81 and 91 extending throughcorresponding contact levers of similar relays 82-92 and 80-9() of othersimilar trunks. While the symbol indicating the central battery has beenrepeatedly shown throughout the drawings, it is to beI understood thatthis is for the sake of simplicity, and that the central battery is tobe arranged in accordance with the well known practice of the art.

Each trunk line leading to a plug, as at C, is provided with a group ofso-called tens relays indicated at 1 2, and with a group of so-calledunit-s relays indicated at 11-12 corresponding generally to thesimilarly characterized relays of the system described in United StatesPatent No. 1,091,193, issued to E. E. Clement March 24, 1914. Assumingfor the purpose of illustration that the line group of Fig. 1 containsone hundred lines, these lines would then be divided into subgroupscorresponding tothe tens digits o t the line numbers. Thus, the firstsubgroup would contain lines numbering 11, 12, 13, 14, 15, 16, 17, 18,19 and'10; the second sub-group would contain lines similarly numbering21 to 20, inclusive, and so on for thc entire hundred. Assuming p thatVten trunks be provided for the one hundred lines, then each trunk wouldbe provided group.

with a tens relay for each sub-group of lines in the contacts of whichwould terminate the line conductors of the respective subgroup. Thus inFig. 1 relayl is the tens relay of the lirst subegroup, and relay 2 isthe tens relay of the second sub-group. The conductors indicated at Eand F are those by which the lines of the first two subgroups areinultipled to corresponding relays of other trunk lines in the group often. Each trunk line is also provided with a group of ten units relayscorresponding respectively to the units digits kof the line numbers.Thus relay 11 corresponds to all lines having numbers ending in theunits digit 1, and ielay 12 to all lines having numbers ending in theunits digit 2. Each trunk is also provided with a relay 71 for causingthe energization of the tens and units relays, and at 72 and 70 I haveindicated those relays of the second and last trunks of the groupcorresponding to relay 71 of trunk C'.

Each group of lines and trunks is provided with a group of seriallyrelated relays corresponding respectively to the several sub-groups. Therelays 101, 102 and 110 correspond respectively to the lirst, second andlast sub-groups of the line group. Ad-

ditional relays for each sub-group are provided, that for the firstsub-group being shown at 141, and for the second sub-group at 142,controlled by the corresponding rer lays of the serially related group.vAnother group of ten serially related relays is provided correspondingto the units digits of contacts corresponds to the group of relays 101,102 and 110; those of the middle' set correspond to the group of relays111, 112 and 120, while those of the right hand set correspond to theseveral trunks of the trunk The switch B remains normally at rest, butin case of delayed selection its wipers are advanced changing the orderof precedence as between the several trunks of the group, and as betweenthe various lines and sub-groups of lines, as will be subsequently.explained. p p

Assuming now that the subscriber at A initiates ra call by raising hisreceiver, a circuit is closed extending from the central battery throughthe winding of relay 41, the lower contact of relay 43, the sub-statioiitransmitter and` receiver, and to earth through the upper contact ofrelay 43. The ensuing energization of relayr 41 disconnects at its'right hand contact lever `the 'winding otcut-ofc relay,` 43 from thecon-l nection terminals at 2214 and 222, and connects these terminals tobattery through a,AV resist-ance coil in order that the line may be heldbusy to outgoing calls during the operation lof the selective apparatus.The circuit closed at the left .hand Contact of relay 41 energizes relay121: rIhe relays 121, 122, l131 andl 132 are to-be'understood ascorresponding respectively to those lines num- -Ybered 11, 121, 21 and22 in the line group of the drawings. The'energization of relay 121closes'atits left hand, contact through wire v145, a guarding circuitcommon to all lines of the entire line group, which will be subsequentlydescribed. The actuation o f the center contact of relay 121 closes acircuit which may be traced .from battery through u ter contact alocking circuit in shunt of the left hand contact of relay 134. TheVleft hand contact of relay 101 completes the circuit of relay 134,which thereuponbreaks the normal circuits leading to the windings.` .Yof each'of the serially relatedgroup of relays, including relay 101, thelatter relay, however, remaining energized because of its lockingcontact having been ypreviously closed. By the actuation of the righthandl contact lever of relay 101, a circuit is completed leading fromground through the left hand wiper of switch B.` the right hand forwardcontact of relay 101, and winding of relay 141 to battery. The operationof, relay 141 closes at its right hand contact an earth connection vforwire 159 leading to the left hand contact'of relay 71. At the same timea circuit is completed'y leading Jfrom ground through the right handcontact,v of relay 121` the center contact of relay 141, wire 155,` theleft hand contact of relay135, the winding of relay 111, wire 151, andto battery throughthe upper contact of relay circuitin shunt of the lefthand contact: of

'- relay 135; completes at its left hand contact The resultingenergization of relay, 7 l111 completes at its center contact a lockingan energizing circuit for relay 135, which thereupon breaks the normalcircuits leading to the windings of the group of relays in which relay111 is located; and at the right hand contact lever of relay 111completes a circuit which may be traced from ground through the centerwiper of switch B, the forward right hand Contact of relay 111, and tothe center contact of relay 71.

By the operations so far described, it will vbe seen that theenergization of local relay 121 of line 11 has resulted in the placingof an earth connection on the left hand contact of relay 71corresponding to the first tens relay shown at 1, and in the placing ofa ground on the middle contact of relay 71 corresponding to the firstunits relay shown at l1. At the same time the actuation of relays 134and 135 Vhas prevented the operation of the associated serially relatedgroups of controlling relays in which are located relays 101 and 111. Ifline No. 12 had been the calling line, then the operation of relay 122would have grounded those contacts of relay 71 corresponding to thefirst tens relay 1, and -to the second units relay 12. Similarly, line21 in calling would energize relay 131 grounding those contacts of relay71 corresponding to the second tens relay 2 and to the rst units relay11.

Assuming that the first idle trunk of the trunk group is that indicatedat C and that the wipers of switch B are resting in the positionindicated, the energization of relay and 89 of trunk C.

A and 81 of the respective relays.

111 has closed a circuit which may be traced from battery through thewinding of relay 71, wire 76, the contact of relay 235 to which thiswire leads, wire 75, left hand contact of relay 81, wire 158, right handwiper of switch B, Wire 152, and to earth at the now closed left handcontact of relay 111. The resulting energization of relay 71 completesat its left hand contact the energizing circuit for relay 1, and at itsmiddle contact the energizing circuit for relay 11. The ensuingenergization of relays 1 and 11 extends the talking conductors 86 and 87of line A to connection with the talking conductors 84 At the same timea circuit is completed at the contacts of these relays leading frombattery through the winding of relay 81, and to earth at the secondcontact down of relay 1. The operation of the right hand contact ofrelay 81 completes through wire 77, left band contact of relay 17 7 wire78 and resistances 13 and 14, locking circuits for relays 11 and 1,respectively, these circuits being completed at contacts 79 By theoperation of relay 71 a circuit has also been closed at its right handcontact leading to battery through the winding of sluggish relay 91. Thetime characteristic of this relay is such that following theinterruption of its circuit at relay 71, it will remain energized for asufficient length of time to prevent the closing of its left handcontact until after ground has been removed from wire 152 by theretraction of the previously energized relay 111 or other correspondingrelay in the same group. The operation of the left hand contact lever ofrelay 81 interrupts the energizing circuit of relay 71, and at itsforward contact extends the circuit of wire 158 to the contact lever ofrelay 91. Upon the subsequent denergization of relay 91, the circuit ofwire 158 is thereby extended to a relay 72 or 70 of the next idle trunkcorresponding to relay 71 of trunk C.

Returning now to relays 1 and 11, the extension of talking conductors 86and 87 by the operation of these relays has completed a circuit whichmay be traced from battery through the winding of impedance coil 179(Fig. 3) conductor 89, conductor 88, conductor 87, and through the lowerwinding of cut-Off relay 43 to earth. The energization of relay 43 overthis circuit interrupts the normal circuits of line A releasing relay 41and connecting the two talking conductors of the line to conductors 87and 86. Additional current will now flow through winding of impedancel79 and the line limbs, then dividing and a portion flowing through theupper winding of relay 43 and a portion to earth through conductors 86,85, 84, and the winding of relay 178 to ground. The release of linerelay 41 releases local relay 121, which in its turn releases relays101, 141, 134, 111 and 1351 thereby resto-ring to normal the controllingcircuits of Fig. 2 leaving them in readiness for a second calling line.The retraction of the right hand contact lever of relay 41 againconnects the contact terminals at 221 and 222 to the lower winding ofrelay 43, and these terminals are now held busy by reason of the batterypotential supplied through the impedance 179. In case of another call,as for example line 21, then the resulting energization of relay 131would cause the operation of relay 72 or the corresponding relay of thenext idle trunk in the serially related group.

Before taking up the operation of the apparatus illustrated in Fig. 3,it should be pointed out that as here illustrated, the trunk lines ofeach group terminate in plugs located each at a different answeringoperators position. Under this arrangement therefore, each plug locatedbefore an answering operator represents a different group of trunklines, and therefore a different group of subscribers lines. Starting,therefore, with the assumption of one hundred subscribers ,lines to agroup and of ten trunks in the group associated therewith, these trunkswould then terminate at ten different operators positions. Assuming thateach operator could handle ten such trunks, there would then be tengroups of lines or one thousand lines divided v into I groups ofonehundred 'and each one hundred line group having access to a groupextending to each one ofthe ten operators of -the system. With thisunderstanding, it is to be explained that relay 235 shown on Fig. 3 is arelay common to that operator before whom is located the plug shownA atC. The circuit represented by vwires 76, 75 and y82 extending to thecontact pieces of relay 235 relates to the group of trunks Y associatedwith line A. The circuit represented by the Wires leading to the lefthand group of contacts of relay 235 relates to an entirely differentgroup of lines and trunks in the system, and relayv235 is to beunderstood to be equipped with as many sets of contacts as there aretrunks like that shown at C terminating at the operators positiontowhich relay 235 belongs... Each such set of contacts therefore controlsthel circuit of a different group of trunks andthe circuit closedthrough the right hand wiperof switch B of any line group mayV thereforeextend through the contacts of each yrelay 235 of the ten operatorspositions.

`Referring back now to the operation of relay 81 following theinitiation of a call at A, the operation of the right hand contact ofthis relay has closed a circuit which may bev traced from. batterythrough lamp 182, the center normally closed contact of relay 175, wire77, and to earth at the right hand contact of relay 81, illuminatinglamp 182 to constitute a call signal for the operator. At the same timea circuit is closed leading from battery through the winding of relay235, the upper contact of relay 176, and to earth through the circuitpreviously traced for lamp V182; The operation of relay 235 by theoperation of that contact lever to which wire 75 leads, disconnects thecircuit of relay 71 of trunk C and extends wire 75 through the forwardengaging contact of wire 82, and thence through the contact of y relay91 to relay 72 of the next trunk in the group containing C. By a similaroperation of the other contact levers of relay 235,

1 the relays corresponding to 71 of all other trunks terminating at theposition of relay 235 are disconnected, and the normal circuits leadingto these relays ar-e extended to the corresponding relays of the trunksnext in serial relation in their respective groups. The relay remainsenergized as long as the lamp 182 or the corresponding lamp of any othertrunk remains illuminated at the operators position with which relay 235is associated; thereby preventing a second call from being extended to atrunk on-such position during such illumination.

Upon observing lamp 182, the operator actuates her listening key H thusconnecting her telephone circuit 191-192with the talking conductors ofthe trunk and her busy multiple jack ofthe desired line, or by plug.

ging into the jack of 'a trunk by means of which the desired connectionmay vbecompleted. Assuming that the plug be inserted into a Jackconnected like that shownat 231,

Fig.v 1, a circuit is first completed leading.

from battery through the winding of'relay 172, the sleeve strand of theplug, the thim ble of jack 231, and to earth through'the winding ofcut-ofi relay a4; rlhe energization of relay 172 at its right handcontact disconnects the busy test circuit leading to 193 completing thetip, strand of the plug circuit; and at its left hand contact completesthe circuit of supervisory lamp 181 and of relay 180. rlhe closing ofrighthand contact of relay 180 energizes relay 175, and the closing ofthe left hand contact of relay 18() completes a circuit for maintainingrelay 174 energized through the ground at left hand contact of relay172. initially energized by the circuit including wire 77 closed atrelay 81, Bearing in mind that relay 17 8v is nowenergized by currentflowing through the sub-station at A, the operation of the upper contactlever of relay 17 5 is atv this time ineffective. The operation of themiddle contact lever of relay 175 interrupts the previously establishedcircuit for lamp 182 extinguishing the lamp; and by the engagement ofthe associated forward contact closes an energizing circuit for relay176. Relay 1276 in operating completes at its lower contact a lockingcircuit leading to the right hand contact of relay 81; and at itsupper'contact interrupts the circuit of relay 235, thereby rendering theother trunk circuits of the operators position available for selection.By the operationv of relays 17 4 and 175 a circuit has been completedeffective to apply ringing current to the line associated with cut-offrelay 44 in a manner now to be explained. For applying ringing currentto the plug indicated at C, I provide sets of cam actuated contacts al,a2, a3 and at. The cams -for actuating these contacts are rigidlysecured" to a common rotating shaft which is driven by a stepping magnet171. A ratchet wheel secured to the common shaft is engaged by a drivingpawl carried by the armature of magnet 171 and ad vanced one step ateach retraction of the magnet armature. The ratchet wheel and shaft maybe regarded as moving always in a clockwise direction and maybe'provided with twelve teeth.

Upon the energization of relay 175 previously described, a circuit maythen be traced leading from battery through the winding of relay 237,contact' of relay 236, winding of magnet 171, right hand forward- Belay174l `was' contact of relay 174, lower forward contact of relay 175, andthence to earth through conductor 77 and the right hand contact of relay81. Current flowing in this circuit venergizes relay 237, 'whichcompletes at its left hand contact a direct battery connection formagnet 171, energizing said magnet, and at its right hand contact anenergizing circuit for relay 236. rThe energization of relay 286interrupts the circuit of relay 287, which thereafter releases itsarmature causing the cams at al, a2, a3 and a4 to be advanced one step.Relays 236 and 237 are sluggish relays, their time characteristic beingsuch that they will continue to vibrate stepping the cams at a suitablerate as long as circuit remains closed through magnet 171. At the firststep of the cams following the insertion of the plug C, the contactlever of each set al, a2, a3 and at is actuated. The lever at 0,1interrupts the normal circuit of the tip cord strand and connects theplug tip with the lever of contacts a2. rlhe operation of this lattercontact lever connects the `lever witha source of alternating ringingcurrent. The operation of contact lever at a3 connects the resistance185 to the sleeve strand of the cord in shunt of the winding of relay172, thereby providing a return path for the ringing current. Theactuation of the contact lever at a4 is without effect at this time.During the second, third and fourth steps of the cams, ringing currentflows over the line of the called subscriber causing the operation ofthe sub-station bell. At the fifth step of the cams contact lever at a2is restored disconnecting the ringing current source and establishing adirect connection between the tip and sleeve of the plug to dischargethe line. At the sixth step, the levers at al and a3 restore, thusrestablishing the talking circuit of the cord strands. Following thesixth step of the cams and assuming that the called subscriber responds,current iiowing through the sub-station telephone is effective .toenergize relay 173, in which case the interruption at the contact ofthis relay extinguishes lamp 181 and releases relay 174. The release ofrelay 174 closes at its right hand contact lever an alternative circuitfor magnet 171 through the contact of cam springs a4, thereby causingthe continued stepping of the cams and associated shaft until coni tactlever a* is restored at the twelfth step of the cams. In case the calledsubscriber does not answer during the first twelve steps of the cammechanism, its cycle of operation is repeated indefinitely until suchresponse has occurred or until the calling subscriber replaces histelephone.

Following the restoration of the receiver of the calling subscribereither in case of no answer from the called subscriber or at theconclusion of conversation, the resulting release of relay 178 causesthe illumination of lamp 182, and with the illumination of lamp 181giving the disconnect signal to the operator. |The plug at C isthereupon removed from the spring jack thereby releasing relay 172. Therelease of relay 172 in-v terrupts at its left hand contact the circuitof' relay 180, which in turn interrupts at its right hand contact thecircuit of relay 175. Relay 175 in dropping back establishes a circuitwhich may be traced from battery through the winding of relay 17 7 themiddle contact of relay 176, the upper contact of relay 175, and thecontact of relay 178. Current in this circuit energizes relay 177 whichactuates its contact interrupting the circuit of wire 78 and therebyreleasing relays 1 and 11, disconnecting the calling line from a trunkline. The interruption at the contacts of relays 1 and 11 releases relay81 which, by the interruption of its right hand contact, releases relay176. The restoration of the left hand contact lever of relay 81restablishes the connection of relay 71, thereby leaving the trunlr Cnow in condition for use with. a subsequently calling line.

Referring now to the switch B, the wire 152 leading to the right handwiper of this I switch may be characterized as a start wire, and whenground is appliedvto this wire by the operation of any one of the seriesof relays, including relay 111, a circuit is closed leading to relay 71of that idle trunk of the associated group most directly connected withthe right hand switch wiper. The `wires leading from the contactsengaged by this wiper are carried directly to the left hand contactlevers of those relays of the vgroup of trunlrs correspondingrespectively to relay 81. By reason of these wires, if the switch B beadvanced the order of precedence as between the several trunks of thegroup is changed at each step of the switch, that trunlr correspondingto the contact upon which the wiper is resting being always the firsttrunk in the order of precedence. Similarly, the wires leading from themiddle group of stationary contacts of the switch B serve to determinethe order of precedence as between the relays of the group containingrelay 111. ln case a plurality of these relays be simultaneously enconnect a calling line with an idle trunk, y

then thel common guarding circuit includr ing wire 1&5 becomes effectiveto cause the advance of switch B and successively change the order ofprecedence as betweenk the several trunks of a group and as between theseveral line groups represented by the left handwiper, and as betweenlthe several lines -of a group as represented by the middle callingline, relay 121l is not released within a normalperiod of time, relay137 becomes denergized. Upon its release an alarmk circuit is closed atN. A. by the 0peration vof its left hand contact; and the closing of itsright hand contact establishes an energizing circuit for switch magnet140' including the contact of relay 138. The

l magnet' 140 on actuation closes at `its upper contact a circuit ofrelay 139. The operation of the lower contactof relay139 closes thecircuit of relay 13S, which in turninterrupts the circuit of drivingmagnet 14:0

causing the wipers' of switch` B to' be ad` vanced one step on theVretraction of the driving magnet armature. At the same time, theinterruption of circuit through wire 151 at the uppercontact of relayr139 releases any previously energized relays in or controlled by thegroups containing relays 101y and 111. The release of the'driving magnetarmature breaks the circuit of relay 139, which upon. restoringreestablishes the circuit of wire 151 allowing the renergization oi"those relays controlled in groups 101 and 111, or of other relayscontrolled in these groups due to the presence of other calling lineswhich may have been placed earlier in order of preference by the advanceof the switch or the release ofthe previously energized relays. Thiso-peration is repeated until by the advance kor the switch B thatportion of the line or trunk apparatus responsible for the delay orfailure has `been withdrawn from service and i all lines then callingproperly selected.

It will be apparent from the above description that each group of trunkstor a group of lines is provided with an individual start wire for thegroup,'and that each start wire is extended through a relay 235 at eachvoperators position. Upon the illumination of a call lampv 182 at anyposition, the operation of the associated relay 235 disconnects theseveral start wires from the several' trunks'of such position extendingthe start wires directly to the trunks of the positionl neX-t serialrelation.r By this positions and a certain number of trunks peroperator, it is to be understood that this distribution of trunks andoperators may be modified to any desired extent. Similarly, the size ofthe line groups and trunk groupsihere assumed has been for purpose or"illustration only and may be modified as desired. My invention is notlimited to the precise arrangement here disclosed, as it maybe embodiedin many different forms.

I claim:

1. A telephone exchange system comprising a plurality of calling linesdivided into sub-groups, a trunk lineA for said plurality i terminatingin a connecting plug' at an operators position, a group of relays forsaid trunk line said relays corresponding indi-Av vidually to thesub-groups'of lines, a group of relays for said trunk line said relayscorresponding individuallyy to corresponding lines in eachsub-group,means for energizing a relay of each of said groups to connectanycalling line with said trunk line,

-a spring jackfor said connecting plug, and

means to maintain a locking circuit for an plug is vresting in saidspring jack.

venergized pair of said relays whilesaid '1 2. A telephone exchangesystem comprising a plurality of calling lines divided into ioosub-groups, a trunk line for said `plurality I terminating in aconnecting plug at an operators position, a group of relays for saidtrunk line said relays corresponding in:-

dividually to the 4sub-groups of lines, a

relays corresponding individually to`corresponding lines in eachsub-group, means for energizing a relay of each of said groups toconnect any calling line with said trunk line, a spring jack for saidconnecting plug, and releasing means for an energized pair of saidrelays placed under control of an associated calling line following theconnection and subsequent,disconnection of said plug with said springjack. y 3. A telephone exchange system comprising a plurality of callinglines divided into sub-groups, a trunk line for said pluralityterminating in a connecting plug at an op- `group of relays for saidtrunk linek said erators position, a group of relays for said tru-nkline said Vrelays corresponding individually to the sub-groups of lines,a group of relays for said trunk line said relays correspondingindividually to corresponding lines in each sub-group, means forenergizing a relay of each of said groups to connect vany callinglinewith said trunk` line, a spring jack for said connecting plug,4 andla-supervisory signal associatedy withy said plug responsive to controlby an associated calling line While said plug is resting in said springack.

t. A telephone exchange system comprising a plurality of calling linesdivided into sub-groups, a trunk line for said plurality terminating ina connecting plug, a group of relays for said trunk line said relaysindividually corresponding to the sub-groups of lines, a group of relaysfor said trunk line said relays individually corresponding tocorresponding lines in each sub-group, switching means for momentarilyenergizing a relay in each group to connect any calling line With saidtrunk line, and a locking circuit for said relays established responsiveto their momentary energization.

5.'A telephone exchange system comprising a plurality of calling linesdivided into sub-groups, a trunk line for said plurality terminating ina connecting plug at an operators position, a group of relays for saidtrunk line said relays corresponding individually to theV sub-groups oflines, a group of relays for said trunk line said relays correspondingindividually to corresponding lines in each sub-group, lmeans forenergizing a relayy of each of said groups to connect any calling linewith said trunk line, means for associating said connecting -r plugvvith the line of a vcalled subscriber, a

supervisory signal associated with saidplug responsive to control by anassociated calling line, and a supervisory signal, associated With saidplug responsive to control A by an associated called line.

G. A telephone exchange system comprising a plurality of calling linesdivided into sub-groups, a trunk line for said plurality terminating ina connecting plug at an operators position, a group of relays for saidtrunk line said relays corresponding individually to the sub-groups oflines, a group of relays for said trunk line said relays correspondingindividually to corresponding lines in each sub-group, means forenergizing a relay of eac-h of said groups to connect any calling linewith said trunk line, means for associating said connecting plug withthe line of a called subscriber, a

supervisory relay for said plug under control of an associated callingline, a supervisory relay for said plug under control of an associatedcalled line, a relay in a local circuit controlled in the manipulation lof said plug, and means controlled by said supervisory and local circuitrelays for controlling the relays oi said groups.

7. A telephone exchange system comprising a plurality of calling linesdivided into sub-groups, a trunk line for said plurality, agroup ofrelays for said trunk line said relays individually corresponding` tothe sub-groups of lines, a group of relays for said trunk line saidrelays corresponding individually to corresponding lines in eachsub-group, a cut-off relay for each calling line, a line relay for eachcalling line, a local relay for each of said line relays, and meanscontrolled by said local relay 'for energizing a relay of each of saidgroups to connect the associated calling line with said trunk line.

8. A telephone exchange system comprising a plurality of calling linesdivided into sub-groups, a trunk line for said plurality terminating ina connecting plug at an operators position, a group of relays for saidtrunk line said relays corresponding individually to the sub-groups oflines, a group of relays for said trunk line said relays correspondingindividually to corresponding lines in each sub-group, means forenergizing a relay of each of said groups to connect any calling lineWith said trunk line, a called line, a spring jack associated therewith,and means controlled by said plug and spring-jack for automaticallyconnecting said called line in circuit with a source of calling current.

9. A telephone exchange system comprising'a plurality of callingv linesdivided into sub-groups, a trunk line for said plurality terminating ina connecting plug at an operators position, a group of relays for saidtrunk line said relays corresponding 'individually to the sub-groups oflines, a group of relays for said trunk line said relays correspondingindividually to corresponding lines in each sub-group, means forenergizing a relay of cach of said groups to connect any calling linewith said trunk line, a called line, a spring jack associated therewith,means controlled by said plug and spring jack for connecting said calledline in circuit with a source of calling current, and means controlledby said called line for discontinuing the connection ofsaid source incircuit therewith.V

lO. A telephone exchange system comprising calling lines, an operatorposition, trunks for said lines each terminating in a connecting plug atsaid position, a signal receiving device associated with each plug,selecting apparatus adapted to connect any calling line With an idle oneof said trunks, selection initiating means Jfor said trunks, and meanscommon to said signal receiving devices for controlling said initiatingmeans,

ll. A telephone exchange system comprisving plural groups of callinglines, an operator position, a trunk for each of said groupe-fv eachterminating in a connecting plug at said position, a signal receivingdevice associated with each plug, selecting apparatus adapted to connectany calling lines With an idle one of said trunks, a selectioninitiating circuit for each of said groups extending to said position,and means common to said signal receiving device for controlling saidinitiating circuits.

12. A telephone exchange system comprising a plurality of calling linesdivided into sub-groups, a trunk line for said plurality terminating ina connecting plug at an operators position, a group of relays for saidtrunk line saidrelays corresponding individually to the sub-groups oflines, a group of relays for' said trunk line said relays correspondingindividually to corresponding lines in each sub-group, means forVenergizing a relay of each of said groups to connect any calling linewith said trunk line, va called line, means associated with said plug`for connecting said called line in circuit with a source of callingcurrent, and means y controlled by said called line for discontinuingthe connection of said source in circuit therewith.

13. A telephone exchange system comprising a plurality oi calling linesdivided into sub-groups, a trunk line for said plurality terminating ina connecting plug at an operators position, a group of relays for saidtrunk line said relays corresponding individually to the sub-groups oflines, a group of relays for said trunk line said relays correspondingindividually to corresponding lines in each sub-groupmeans forenergizing a relay of each of said groups to connect any calling. linewith said trunk line, a called line, and means manually controlled atsaid position for automatically connecting' said luo and line in circuitvvith a;source of, P z-i calling current.

14. A telephone exchange system comprising a plurality of calling linesdivided into sub-groups, a trunk line for said lines terminating in aconnecting plug at an operator position, a group of relays for saidtrunk line said relays corresponding individually to 'the sub-groupsuoflines, a group of relays for said trunk line said relays correspondingindividually to corresponding lines 'in each sub-group, means forenergizing a pair of relays one from each of said groups to connect anycalling line with said trunk line, a locking circuit for said pair ofrelays, and operator controlled means to break said locking circuitfollowing use of said trunk line.

15. A telephone exchange system comprising a plurality of calling linesdivided into sub-groups, a trunk line for said lines terminating in aconnecting plug at an operator position, a group of relays for saidtrunk line said relays corresponding individually to the sub-groups oflines, a 'group of relays for said trunk line said relays correspond'-ing individually to corresponding lines in each sub-group, means forenergizing a pair of relays onel from each of said groups to connect anycalling line With said trunk line, and means to prevent energizing any.

relay of said groups other than said pair.

16. A telephone exchange System compriss groups, a cut-ofi relay foreach line, a trunk line for said lines terminating in a coning aplurality of calling lines divided int-o necting plug at an operatorposition, a group l of relays for said trunk line said relayscorresponding individually to the sub-groups of lines, a group of relaysfor said trunk line said relays corresponding` individually tocorresponding lines in each sub-group,-vv

means or energizing a pair of relays one from each of said groups toconnect the talking conductors of any calling line With'said trunk line7and a separate local .conductor including contacts of said pair ofrelays for controlling said cut-oft1 relay. f 17, A telephone exchangesystem comprising a plurality of calling lines divided into sub-groups,a trunk line for said lines termiing individually to corresponding linesin :ssiA

each sub-group, means fo-renergizing a pair of relays one from each ofsaid groups to' connect the tallring conductors of any calling line withsaid .trunk line, and a separateA local conductor including contacts of.said pair of relays for controlling said pair o'f` relays.

18. A telephone exchange system compris-v fico sub-groups, a trunk linefor said lines terininating ina connecting' `plug at an operatorposition, a group of relays for' said trunk line said relayscorresponding individually to the sub-groups of lines, a group'of relaysfor said trunk line said relays corre-- spending individually tocorresponding lines in each sub-group, means for energizing a pair ofrelays yone from each of said groups to connect the talking conductorsof iioA any calling line With said trunk line, a locki ing circuit forsaid pair of relays, and a separate local conductor including contactsof said pair of relays for controlling said locking circuit.

19. A telephone exchange system comprising a plurality of calling linesdivided intol sub-groups, a trunk line for said lines terminating in aconnecting plug at an operator position, a group of relays for saidtrunk line said relays corresponding individually to the sub-groups oflines, a group ofrelays for said trunk line said relays correspondinglindividually to corresponding lines in each sub-group, means forenergizing a pair of relays one from each of said groups to connect thetalking conductors of any calling line With said trunk line, a lockingcircuit for said pair of relays, a separate local conductor includingcontacts of said pair of relays, and means controlled by said localconductor for establishing said locking circuit. a

20. A telephone exchange system comprising a plurality of calling linesdivided into sub-groups, a trunk line for said lines terminating in aconnecting plug at an operator position, a group of relays for saidtrunk line said relays corresponding individually to the sub-groups oflines, a group of relays for-said trunk line said relays correspondingindividually to corresponding lines in each sub-group, means forenergizing a pair of relays one from each of said groups to connect anycalling line With said trunk line, a locking circuit for said pair ofrelays, and means including serially related contacts of said pair ofrelays for establishing said locking circuit.

2l. A telephone exchange system comprising a plurality of calling linesdivided into sub-groups, a trunk line for said lines terminating in aconnecting plug at an operator position, lan indicator for said trunkline,a group, of relays for said trunk line said relays correspondingindividually to thev sub-groups of lines, a group of relays for saidtrunk line said relays correspondingindividually to corresponding linesin each sub-group, means for energizing a pair of relays one from eachof said groups to connect the talking conductors of any calling lineWith said trunk line, and a separate local conductor including contactsof said pair of relays for controlling said indicator.

22. A telephone exchange system comprising a plurality of calling linesdivided into sub-groups, a trunk line for said lines terminating in aconnecting plug at an operator position, a group of relays for saidtrunk line said relays corresponding individually to the sub-groups oflines, a group of relays for said trunk line said relays correspondingindividually to corresponding lines in each sub-group, means forenergizing a pair of relays one from each of said groups to connect thetalking conductors of any calling line With said trunk line, and aseparate local conductor including contacts of said pair of relays forcontrolling said energizing means.

23. A telephone exchange system comprising a plurality of calling linesdivided into sub-groups, a trunk line for said lines terminating in aconnecting plug at an operator position, a group of relays for saidtrunk line said relays corresponding individually to the sub-groups oflines, a group of relays for said trunk line said relays correspondingindividually to corresponding lines in each sub-group, means forenergizing a pair of relays one from each of said groups to select andconnect the talking conductors of any calling line, selection initiatingmeans for said lines, and a separate local conductor including contactsof said pair of relays for controlling said initiating means.

24. A telephone exchange system comprising a plurality of calling linesdivided into sub-groups, a trunk line for said lines terminating in aconnecting plug at an operator position, a group of relays for saidtrunk line said relays corresponding individually to the sub-groups oflines, a group of relays for said trunk line said relays correspondingindividually to corresponding lines in each sub-group, means forenergizing a pair of relays one from each of said .groups to select andconnect the talking conductors of any calling line, selection initiatingmeans for said lines associated With said trunk line, and a separatelocal conductor including contacts of said pair of relays fordisassociating said initiating means from said trunk line.

25. A telephone exchange system comprising a plurality of calling linesdivided into sub-groups, a trunk line for said lines terminating in aconnecting plug at an operator position, a group of relays for saidtrunk line said relays corresponding individually to the sub-groups oflines, a group of relays for said trunk line said relays correspondingindividually to corresponding lines in each sub-group, means forenergizing a pair of relays one from each of said groups to connect thetalking conductors of any calling line with said trunk line, a separatelocal conductor including contacts of said pair of relays, another trunkline, and means controlled by said local conductor for associating saidother trunk line vvith said lines.

26. A telephone exchange system comprising a plurality of calling linesdivided into sub-groups, a trunk line for said lines terminating in aconnecting plug at an operator position, a group of relays for saidtrunk line said relays corresponding individuallyrto the sub-groups oflines, a group of relays for said trunk line said relays correspondingindividually to corresponding lines in each sub-group, means forenergizing a pair of relays one from each of said groups to connect thetalking conductors of any calling line With said trunk line, a separatelocal conductor including contacts of said pair of relays, and ringingmeans for said plug controlled by said local conductor.

27. A telephone exchange system comprising a plurality of calling linesdivided into sub-groups, a trunk line for said lines terminating in aconnecting plug at an operator position, a group of relays for saidtrunk line said relays corresponding individually to the sub-groups oflines, a group of relays for said trunk line said relays cor- CLGresponding individually to corresponding lines in each sub-groups meansfor energizing a pair of relays one from each of said groups to connectthe talking conductors of any calling line with said trunk line, and aseparate local conductor for said trunk line including serially relatedcontacts of said pair of relays.

28. A telephone exchange system com-prising a plurality of calling linesdivided into sub-groups, a trunk line for said lines ter minating in aconnecting plug at an operator position, a group of relays for saidtrunk line said relays corresponding individually to the sub-groups oflines, a group of relays for said trunk line said relays correspondingindividually to corresponding lines in each sub-group, means forenergizing a pair of relays one from each oi said groups to connect thetalking conductors of any calling line With said trunk line, a lockingcircuit for said pair of relays, and a local circuit for said Atrunkli-ne separate from said talking conductors controlled by said lockingcircuit.

29. A telephone exchange system comprising a plurality of calling linesdivided into sub-groups, a trunk line for said lines terminating in aconnecting plug at an operator position, a group of relays for saidtrunk line said relays corresponding indi-L vidually to the sub-groupsof lines, a group of relays for said trunk line said relayscorresponding individually to corresponding lines in each sub-group,means for energizing a pair of relays one from each of said groups toconnect the talking conductors of any calling line with said trunk line,a locking circuit for said pair of relays, andv a local circuitincluding contacts of said pair of relays separate from said conductorscontrolled by said locking circuit.

30. A telephone exchange system comprising a plurality of calling lines,a trunk line for said lines terminating in a connecting plug at anoperator position, a group of relays, means for energizing certain ofsaid relays to connect any calling line With said trunk line, operatorcontrolled means for said trunk line, and a locking circuit for saidcertain relays maintained until after actuation of said operatorcontrolled means.

3l. Atelephone exchange system comprising plurality oit' calling lines,a trunk line for said lines terminating in a connecting plug at anoperator position, a group of relays, means for energizing certain ofsaid relays to connect any calling line With said trunk line, operatorcontrolled means for said trunk line, and a signal to'indicateconnection of a calling line maintained active until after actuation ofsaid operator controlled means. f

32. A telephone exchange system comprising a plurality of calling lines,a trunk line for said lines terminating in a connecting;

plug at an operator position, a group of. relays, means for energizingcertain of said relays to connect any calling line With saidV trunkline, a spring jack for connecting to4 a Wanted line, and means to'prevent de? energization of said certain relays during the presence ofsaid plug in said spring jack.

33. A telephone exchange system comprising a plurality of calling lines,a trunk line for said lines terminating in a connecting, plug at anoperator position, a group of -re# lays, local relays for momentarilyenergize.

energizing certain relays of said group to connect any calling line'With said trunk line. K-

35. A telephone call Adistributing rsystem comprising a plurality of'calling' lines, aplurality of operatorspositions, a plurality of trunksterminating at each operators position, means for selecting idle trunksand comiecting calling lines therewith,` a

plurality of circuits extending to the trunksv at each position overWhich such selecting means may be started in operation, operatorcontrolled means associated with each' trunk, a device common to theposition controlled from said operator controlled means for temporarilydisabling the starting circuits extending to such position.

36. A telephone call distributing vsystem comprising a plurality ofcalling lines, a plurality of operators positions, a plurality of trunksterminating at each operators position, means for selecting idle trunksand connecting calling lines therewith, a plurality of circuitsextending tothe trunks at each position over WhichA such selecting meansmay be started in operation, operator controlled means associated vvithreach trunk, a relay common to the position controlled from said operatorcontrolled means for temporarily disabling the starting cir-vy cuitsextending to such position.

37. A telephone call distributing system comprising a plurality of linesarranged in groups, a plurality of operators positions, a plurality oftrunks terminating at each position, selecting means for associatingcalling lines of each group With trunks at each position, circuits forstarting such selecting means in operation extending from a plurality ofgroupsof lines to each position, operator controlled means at eachVoperators position, and a device common to the position, for disablingall of the starting circuits extending t0 such position, renderedoperable by such operator controlled means.

38. A telephone call distributing system comprising a plurality of linesarranged in groups, a plurality of operators positions, a plurality oftrunks terminating at each position, selecting means for associatingcalling lines of each group With trunks at each position, circuits forstarting such selecting means in operation extending from a plurality ofgroups of lines to each position, a call signal individual to each trunkadapted to be displayed when a calling line is connected to such trunk,and a device rendered operable during the display of such signal fortemporarily disabling all of the starting circuits extending to theposition at which such trunk terminates.

In Witness whereof, I aliix my signature in the presence of twoWitnesses.

HARRY Gr. WEBSTER.

Witnesses:

A. C. STUART, J. D. BONNAR.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents,

Washington, D. C.

